Hopper: java.lang.IllegalArgumentException: Modifier name cannot be empty

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-145626/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pr.<init>(SourceFile:31)
	at up.a(SourceFile:92)
	at zg.D(SourceFile:595)
	at zg.a(SourceFile:482)
	at azi.a(SourceFile:73)
	at bai.a(SourceFile:167)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 13-9-13 15:36
Description: Rendering screen

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pr.<init>(SourceFile:31)
	at up.a(SourceFile:92)
	at zg.D(SourceFile:595)
	at zg.a(SourceFile:482)
	at azi.a(SourceFile:73)
	at bai.a(SourceFile:167)
	at bia.b(SourceFile:720)
	at awo.V(SourceFile:717)
	at awo.e(SourceFile:646)
	at net.minecraft.client.main.Main.main(SourceFile:103)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pr.<init>(SourceFile:31)
	at up.a(SourceFile:92)
	at zg.D(SourceFile:595)
	at zg.a(SourceFile:482)
	at azi.a(SourceFile:73)
	at bai.a(SourceFile:167)

-- Screen render details --
Details:
	Screen name: bat
	Mouse location: Scaled: (450, 200). Absolute: (900, 617)
	Screen size: Scaled: (960, 509). Absolute: (1920, 1017). Scale factor of 2

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bfz['HOI_SIMON'/29, l='MpServer', x=207,19, y=57,62, z=-1093,48]]
	Chunk stats: MultiplayerChunkCache: 316, 316
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (8,64,8), Chunk: (at 8,4,8 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 3976729 game time, 6000 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 22 total; [th['entity.EnderCrystal.name'/8, l='MpServer', x=164,50, y=63,00, z=-1127,50], bfz['HOI_SIMON'/29, l='MpServer', x=207,19, y=57,62, z=-1093,48], pb['entity.ItemFrame.name'/9, l='MpServer', x=164,50, y=59,50, z=-1076,06], ty['entity.MinecartRideable.name'/10, l='MpServer', x=195,00, y=56,34, z=-1121,88], tq['Boat'/11, l='MpServer', x=194,71, y=56,28, z=-1117,22], sq['Donkey'/12, l='MpServer', x=202,97, y=56,00, z=-1098,00], sq['Mule'/13, l='MpServer', x=204,33, y=56,00, z=-1102,52], pb['entity.ItemFrame.name'/14, l='MpServer', x=199,50, y=58,50, z=-1087,06], pb['entity.ItemFrame.name'/15, l='MpServer', x=200,50, y=58,50, z=-1087,06], vb['Villager'/17, l='MpServer', x=200,69, y=57,00, z=-1051,69], vb['Villager'/16, l='MpServer', x=202,56, y=57,00, z=-1051,31], pb['entity.ItemFrame.name'/19, l='MpServer', x=218,06, y=58,50, z=-1085,50], sq['Horse'/18, l='MpServer', x=206,91, y=56,00, z=-1098,72], pb['entity.ItemFrame.name'/21, l='MpServer', x=216,50, y=56,50, z=-1087,06], pb['entity.ItemFrame.name'/20, l='MpServer', x=222,50, y=58,50, z=-1083,06], pb['entity.ItemFrame.name'/23, l='MpServer', x=234,50, y=58,50, z=-1083,06], pb['entity.ItemFrame.name'/22, l='MpServer', x=223,50, y=58,50, z=-1083,06], pb['entity.ItemFrame.name'/25, l='MpServer', x=261,50, y=58,50, z=-1083,06], pb['entity.ItemFrame.name'/24, l='MpServer', x=258,50, y=57,50, z=-1083,06], pc['entity.LeashKnot.name'/27, l='MpServer', x=204,50, y=56,50, z=-1101,50], pc['entity.LeashKnot.name'/26, l='MpServer', x=206,50, y=56,50, z=-1097,50], pc['entity.LeashKnot.name'/28, l='MpServer', x=209,50, y=56,50, z=-1097,50]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bfu.a(SourceFile:285)
	at awo.b(SourceFile:1821)
	at awo.e(SourceFile:655)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 13w37b
	Operating System: Windows 8 (x86) version 6.2
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 44512968 bytes (42 MB) / 328663040 bytes (313 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 976 (54656 bytes; 0 MB) allocated, 8 (448 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 13w37b
	LWJGL: 2.9.0
	OpenGL: AMD Radeon HD 7470 GL version 4.2.11750 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1465 (82040 bytes; 0 MB) allocated, 43 (2408 bytes; 0 MB) used

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-145626/10438820/